1. Field of the Invention
The present invention relates to a zoom lens and an electronic imaging device having the zoom lens, and in particular, to an electronic imaging device, such as a video camera or a digital camera, in which a slim design of the camera in depth is achieved by considering the optical system of a zoom lens, and a zoom lens used in this electronic imaging device.
2. Description of Related Art
Recently, as a camera for the next generation of an alternative to a silver halide 35 mm film (135 format) camera, special attention has been devoted to a digital camera (an electronic camera). Such digital cameras have come to have many categories in a wide range from a high-function type for business use to a popular portable type.
The thickness of an optical system, notably a zoom lens system, from the most object-side surface to an imaging plane constitutes the greatest obstacle to a reduction in depth of a camera.
The slim design technique of a camera body chiefly used in recent years adopts a so-called collapsible lens barrel that although the optical system protrudes from the front side of the camera body in photography, it is incorporated in the camera body when the camera is not used.
Examples of optical systems having possibilities that the collapsible lens barrel is used and the slim design is effectively achieved are set forth in Japanese Patent Kokai Nos. Hei 11-194274, Hei 11-287953, and 2000-9997. Each of the optical systems includes, in order form the object side, a first lens unit with negative refracting power and a second lens unit with positive refracting power so that when the magnification of the optical system is changed, both the first lens unit and the second lens unit are moved.
Recently, an electronic imaging device which does not have rising time (lens shifting time) required to bring the camera into the working state as in the collapsible lens barrel and is favorable for water and dust proof has been proposed. In order to make the camera extremely small in depth, the optical system of the electronic imaging device is constructed so that the optical path (optical axis) of the optical system is bent by a reflecting optical element such as a mirror or prism. Specifically, the most object-side lens unit is constructed as a position-fixed lens unit, in which the reflecting optical element is provided. The optical path varying behind this lens unit is bent in a longitudinal or lateral direction of the camera body so that the smallest possible dimension of the depth is obtained.